Camera Input

Mirror scanning low cost low duty camera

A line following robot using a video camera as the only sensor with binary image and video output.

August 2003 MassMind Newsletter - Easy Vision Systems

Serial Protocols of Some Digital Cameras

Also:

• Light Sensors@,
• AntiCamera@,
• Optical Ranging@

Images Sensors

• CCD
• CMOS
  • http://www.zoran.com/products/camera/zr32112.asp 1.3 Megapixel,  Color or Black and White, I2C control and 10 bit image output.
  • http://www-2.cs.cmu.edu/~cmucam/index.html The CMUcam Vision Sensor uses a cmos camera ( from http://www.electronics123.com/amazon/catalogue/c3-1-5.htm ) and an Ubicom SX28 chip to detect motion, track objects and motion and capture images via a serial port.

  • Gameboy video cameras

    128x128 1" round or 0.7"x0.7" B/W. These camera's are based on the Mitsubishi CMOS image sensor chip. The chip itself is quite intelligent with the ability to a 3x3 filter on the image in real time. Takes a processor to set up and run it. See also:

    • http://homepages.paradise.net.nz/~vkemp/gbcam.htm
    • http://www.lh.co.nz/hardware
    • http://pages.zoom.co.uk/andyc/avr.htm System for grabbing images from a GameBoy camera . circuits (big gif schematic and eagle designs), assembly control code, JavrBasic shell and Win95 viewer program, just follow the ACARV link.
    • http://minyos.its.rmit.edu.au/~s9906768/pic/proj_gbc.html

Sir Douglas says:

For people with Large Screen TV hooked up to their computer that want a Free GREEN SCREEN:

All they have to do is make a movie of a GREEN background or change their DESKTOP to be NO ICONS and GREEN in color and view it on their large screen TV. Then they can stand in between the TV's Green Screen and their movie camera and make awesome Movies.

The problem with Green screens is that you need a lot of light to avoid shadows which produce different shades of GREENS; However, if you use a Large Screen DLP the back-lit background will produce NO variation of GREENS.

Sure it is only good for people that don't have money that want to produce YouTube videos... but still it does work very well.

Has anybody ever tried:

1. using two oscillating mirror (mounted to the end of the motor shaft on a wedge) with (very) different speeds to generate a Lissajou pattern with a large number of left-right oscillations per up-down oscillation. see: http://www.hut.fi/~then/mytexts/lasercontrol.html
2. software map the original raster pattern to the Lissajou pattern. I.e. spread the pixels where the beam is traveling slow (at the edges) and compress them where it is traveling fast (in the middle)
3. electronically modulate a visible laser diode with the pixel data with the start of each scan line triggered by the beam passing a photo diode between the first (horizontal) and second (vertical) mirrors and frame synced by another after the second mirror

The point here is that the two motor driven mirrors can spin very quickly with little current draw while generating an (almost) raster scan pattern that is corrected for by software. You can reduce the need for mapping by not starting the scans until the beam is a bit away from the edge.

Andy Howard says:

A technique similar to this was used in some of the very earliest electro-mechanical TV experiments. Spinning drums with mirrors attached all around to form a regular polygon were used to give scanning with near-instant flyback.

I've recently seen a similar-looking arrangement used with a lightshow laser to project computer-generated video snippets.

See also:

• http://www.hkvstar.com/technology-news/ccd-vs-cmos-in-video-surveillance-cameras.html Comparison between CCD and CMOS for video surveillance technology.
• http://code.google.com/p/mobilewebcam-android/ Open source automatic upload app for Android phones. Many features, including motion detection and support for HTTP, FTP, SMTP, upload. James Newton of MassMind replies: This is how the motion detection works (done every frame): 1. convert preview image to grayscale 2. erode filter (which means making every pixel the max color of its neighbours) 3. calc difference to last image. This is where the color parameter is used. Whenever the eroded gray difference changes more than this value this pixel is counted as changed check this count of changed pixels. Here the second parameter is simply compared to that count -> more changed than Motion Trigger -> motion detected! In the sourcecode it is the PreviewImageChecker in Preview.java ...

• https://code.google.com/p/linear-book-scanner/ Google has open sourced their book scanning system "Linear Book Scanner is a prototype automatic book scanning device. The device moves a book face-down over linear sensors to capture page images, and uses vacuum pressure to turn pages automatically as the book moves. "
• http://www.funsci.com/fun3_en/ucomp1/ucomp1.htm Building a cheap microscope. Lots of practical information on optics.
• http://www.cs.cmu.edu/afs/cs/project/cil/ftp/html/vision.html Computer Vision Homepage
• http://kitsrus.com $50 cmos 16mm cube video cammers
• Structured Light Vision - demo program
• http://www.supercircuits.com/ $30 B/W NTSC
• http://www.vvl.co.uk.
• http://www.phototimes.com
• http://www.propic2.com/camera/camera.htm
• PIC Abstractions - Compact Optical Image Scanner - $15 prototype scans 64x64 and xmits RS232
  
• Book "PHOTODIODE AMPLIFIERS, OP-AMP SOLUTIONS" by Jerald Graeme
• http://www.average.org/digicam/ Fujitsu chipset protocal docs (cached 200007310802)
• http://www.asahi-net.or.jp/~xg2k-hys/index-e.html Casio QV-10/100/770 cameras serial communication protocol and *nix/win/680x0 source.
• Suppliers
  • http://www.taosinc.com have taken over the TI parts
  • http://www.sel.sony.com/semi
  • http://www.sony.co.jp
  • http://www.intl.samsungsemi.com
  • http://www.mec.panasonic.co.jp

See:

Comments:

• http://www.scdlink.com Security Cameras Direct at www.scdlink.com has some of the best small cameras and mini transmitters found anywhere. Has anyone else received there catalog. If not you can call them at 800-316-6027.